With increasing development of mobile computing technology industries, a variety of portable electronic apparatuses such as personal digital assistants (PDAs), notebook computers or mobile phones are constantly improved. The development and improvement make these electronic products essential because they are feasible to be used in many instances. On account of their portability, the portable electronic apparatuses fabricated according to the mobile computing technologies are usable wherever and whenever the users are. In case no external power supply is provided, a built-in power supply such as a battery is usually employed as the main power source. Since the power supplied from the battery is limited, the power-saving means used in the portable electronic apparatus is taken into consideration.
Take the power-saving means used in the general personal computers or notebook computers for example. Many kinds and levels of power-saving modes are selectively used to achieve the purpose. One of the examples is so-called as ACPI (Advanced Configuration and Power Management Interface). ACPI is a specification defining standard interfaces for hardware configuration and power management of the power-saving means. According to the ACPI specification, the central processing unit (CPU) of the computer enters in various power-saving modes or a sleeping state when the user lets the operation system lie idle, thereby adjusting power consuming amount of the CPU, the hard disc, the display or the memory. Such power-saving means is widely used, especially in notebook computers for providing an effective power-saving and power management mechanism. As known, in some operation systems such as Windows, the power-saving means can be set manually according to the user's requirement and the power supply conditions.
Nowadays, somebody may have experience of watching cable TV programs through a personal computer. The TV signals can be transmitted to the personal computer by externally connecting a TV box to the computer or inserting a TV card conforming to the specification of a peripheral component interconnect (PCI) interface into a slot of the computer. Accordingly, the TV signals can be displayed on the display. Under this circumstance, the personal computer has advantageously functions as a TV set. Likewise, the cable TV programs can be shown on the display of the notebook computer by the similar technology. Please refer to FIG. 1(a), which is a schematic block diagram illustrating the configuration of playing cable TV programs on a notebook computer 10. As shown in FIG. 1(a), a cardbus adapter 11 is inserted into the notebook computer 10 and electrically connected to a signal input terminal of the cable TV 12. In such way, the TV programs can be displayed on the display of the notebook computer 10. Alternatively, a built-in TV card in communication with the signal input terminal of cable TV 12 can be provided in the notebook computer 10 to achieve the same purpose.
As known, the power-saving technology of the TV module, e.g. the TV card or the cardbus adapter, are independent of the power management system of the CPU of the notebook computer. For most notebook computers, the power-saving means is operated in an automatic mode and fails to be adjusted according to the user's demands. In consequence, the performance of the notebook computer is not optimized when the notebook computer is employed to play TV programs. Typically, the TV card or the cardbus adapter has several integrated circuits (ICs), including a TV tuner, a video decoder, a TV demodulator and the like. In a case that no power-saving means is taken, after the TV module containing these integrated circuits is built in or inserted into the notebook computer to be in communication with the notebook computer, the TV tuner or the video decoder will still be maintained in a stand-by state. Even if the TV module has not been used for playing the TV programs, the TV tuner or the video decoder in the stand-by state will continuously decode and transmit the TV signals. Under this circumstance, the power required for decoding and transmitting the TV signals is supplied from the notebook computer such that the battery consumes more energy. Whereas, in a case that the power-saving means is operated in the automatic mode, the related ICs of the TV module are shut off to enter the TV module in the power-saving mode when the TV module has not been used for playing the TV programs.
Referring to FIG. 1(b), a flowchart of a power control method used with the TV module of the notebook computer 10 is illustrated. First of all, after the notebook computer is activated, the TV module will automatically detect whether the TV module is operating. If the TV module is playing the TV programs, the power-saving mode of the TV module is suspended to make the TV module operate in a normal mode. Otherwise, the TV module enters the power-saving mode when the TV module is not playing the TV programs so as to disable the related ICs of the TV module and save power consumption of batteries contained in the notebook computer 10. The above procedures are automatically implemented according to the settings of the TV module but fail to be changed or set by the user. Under this circumstance, if the system has idled for a time period or the user intends to watch the TV programs, the related ICs of the TV module should be successively activated again. Since it takes a long time for the notebook computer 10 to successively activate or wake up the related ICs of the TV module, this power-saving operation is not user-friendly. Moreover, to determine if the TV module should enter the power-saving mode just depending upon whether the TV module is playing the TV programs. This power-saving operation is unsatisfied and inefficient.
In views of the above-described disadvantages resulted from the prior art, the applicant keeps on carving unflaggingly to develop a power control method through wholehearted experience and research.